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This question seems abandoned, there is not further information or activity added to it for several months. I am flagging this to be closed by a moderator. If you think this issue is still affecting you you can flag a moderator to re-open it.
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Bruno PereiraFeb 2 '12 at 22:53

I can start you on your way, although this might need some more padding from someone with an ATI card.

You'll probably need the propriety (i.e. from the manufacturer, rather than open source) drivers installed. There should be an notification looking for your attention, but I'm not sure where it appears in Kubuntu. In lieu of that you can use:

sudo jockey-text

This should get you up to speed with your drivers, if you aren't already.

For the dual monitor you may be able to use 'Monitors' in the 'Control Center' to make it dual screen (rather than cloned.) It is possible, like nvidia, that you'll have to use ATI's software, however. A quick google search has suggested you try this:

kdesu aticonfig --initial

Not being sure, however, I'd recommend you back up your video configuration first; just to be safe: